This is the
fourth of 10 lectures on toxicologic epidemiology. It has been prepared to expand on the
brief discussion of the linkage between health risk assessment (RA) and epidemiology that
was presented in Lecture 1. As mentioned in Lecture 3 on toxicology and RA, the close relationship
between RA and epidemiology likewise cannot be fully disclosed in one or two lectures of
this type. The documentation and literature on such a relationship is simply too much to
appreciate. Accordingly, this lecture is necessarily compact, with the materials organized
primarily for easy access by the novice.

The relationship between epidemiology and RA is
essentially the same as discussed in the last lecture between toxicology and RA, at least
in scope. As a matter of fact, if epidemiologic studies on health effects were ethical and
as readily available as animal studies and in vitro assays are, there would be no
need to provide the last lecture on toxicology and RA. Nor would there be a need to
separate toxicologic experiment from human testing or clinical trials. The discussion in
this lecture hence will be more focused and specific, at the expense of a broader, more
general presentation already given in Lecture 3.